飞秒激光角膜原位磨镶术手术前后散射变化及其影响因素分析

Analysis of changes in stray light and relevant factors before and after femtosecond laser in situ keratomileusis

背景准分子激光角膜原位磨镶术（LASIK）是近年来新兴的屈光手术方式，其术后的视觉质量越来越受到关注。散射光是一项评价视觉质量的重要指标，近年来不同屈光手术前后散射光变化及其影响因素的研究是一个热点问题，研究飞秒LASIK手术后散射光的变化对术后视觉质量的评价具有重要意义。目的观察飞秒LASIK手术前后散射光的变化，并对其影响因素进行分析。方法回顾性分析2010年12月至2011年2月在天津市眼科医院行飞秒LASIK的近视及近视散光患者55例109眼的临床资料，对患者术前，术后1d、1周、1个月和6个月应用C—Quant散射光计量仪测量的散射光计量值变化进行分析，并分析各时间点散射光计量值变化与术前年龄、等效球镜度、瞳孔大小和中央角膜厚度（CCT）的关系，分析术后各时间点散射光计量值变化与残余角膜植床厚度（RBT）、RBT／CCT、切削深度、切削比、设定瓣厚度、角膜瓣直径、蒂宽、能量之间的关系。结果飞秒LASIK术前，术后1d、1周、1个月和6个月测得的散射光计量值分别为0．90_＋0．19、1．10-＋0．19、1．02_＋0．18、0．96±0．16和0．94±0．15，各时间点间所测散射光计量值的总体比较差异有统计学意义（F=17．699，P=0．000），术后1周的散射光计量值明显高于术后6个月，差异有统计学意义（t=2．412，P=0．017），术后1个月与术后6个月术眼的散射光计量值差异无统计学意义（t=0．779，P=0．437），术前和术后6个月散射光计量值差异无统计学意义（t=-1．877，P=0．062）。术前散射光计量值与年龄、等效球镜度、瞳孔大小和CCT均无明显相关性（P〉0．05）；术后1周、1个月及6个月散射光计量值变化与切削深度均呈负相关（r=0．226、-0．228、-0．241，P〈O．05），与切削比均呈负相关（，=-0．149、-0．219、-0．255，P〈0．05）。结论飞秒LASIK术后1个月内散射光计量值增加，术后6个月恢复正常。术后散射光计量值的变化可能与手术中选择的多种参数和因素有关。

Background As a newly developed refractive surgery,femtosecond laser in situ keratomileusis （LASIK） receives more and more attention. Changes in ocular stray light after femtoseeond LASIK is an important problem that impacts visual quality. Some relevant research has been performed before, but the outcomes are conflicting. Objective This primary study was to investigate the change of stray light values before and after femtoseeond LASIK and analyze the relevant faetors underlying the change. Methods Clinical data from 109 eyes of 55 myopic patients who underwent femtoseeond LASIK in Tianjin Eye Hospital from December, 2010 through February,2011 were included in this study. Stray light values were measured and recorded by C-Quant stray light meter preoperatively, and 1 day, 1 week, 1 month and 6 months postoperatively. The stray light data were compared by repeated measures ANOVA,and the correlations among the stray light values with preoperative factors, such as age, equivalent sphere, pupil diameter and central corneal thickness （CCT） , as well as with postoperative factors, such as residual bed thickness （RBT） , RBT/CCT, ablation depth, ablation ratio, flap thickness, flap diameter flap base width and exiting energy, were analyzed statistically. Written informed consent was obtained from each individual at initial of this study. Results The stray light values were O. 90-＋0. 19,1.10_＋0. 19,1.02-＋0. 18,0.96_＋0. 16 and 0. 94-＋0. 15 pre-operation,and 1 day, 1 week, 1 month and 6 months after femtosecond LASIK. The stray light values increased significantly 1 day,1 week,and 1 month after surgery, showing significant differences among the various time points （F= 17. 699,P = 0. 000）. The mean stray light value was higher in 1 week than that in 6 months after operation （t=2. 412 ,P=O. 017 ）. No significant differences were found in the stray light values between 6 months and 1 month or pre-operation （ t = 0. 779, P = 0. 437 ; t = - 1. 877, P = 0. 062 ）. No significant correlations were seen between preoperative and postoperative stray light values with age, preoperative refractive diopter, pupil diameter or CCT （P〉0.05）. The changes in stray light values 1 week, 1 month and 6 months after surgery were negatively correlated with ablation depth（ r= -0. 226,-0. 228, -0. 241 ;P〈0. 05 ） and ablation ratio（ r = -0. 149, -0. 219, -0. 255 ;P〈0. 05 ）. Conclusions Stray light values increase within 1 month and return to normal 6 months after femtosecond LASIK. Stray light values may be related to multiple setting laser parameters and factors during femtosecond LASIK.